The proposed research concerns the development of young infants' cries and the perception of cries by parents and nonparents. Previous research has demonstrated that infants' cries reflect the health status of the infant, and some authors have speculated that infants with particularly aversive cries may be more likely than other infants to be abused by their parents. The precise acoustic basis of the perception of cries as aversive has not yet been elucidated, however. Further, most prior studies have focused on neonatal pain cries as stimuli. The proposed research will examine instead infants' hunger and discomfort cries, which parents hear everyday, and will determine the role that several acoustic measures play in the perception of cries as aversive. In addition, the differentiation of the early "basic" cry into several different signals will be examined. The short- and long-term stability of acoustic characteristics of cries will be determined. Finally, behavioral responses to cries that differ in perceived aversiveness and in controllability will be measured. Four studies are proposed: The first will determine experimentally the acoustic basis of nonparents' perceptions of cries as aversive. Electronic manipulations of hunger cries will be used to determine how timing, intensity, and frequency contribute to the aversive quality of cries. The second study will generalize the findings of Study 1 to parents, measure the short-term stability of acoustic properties of cries, and relate parents' perceptions of the aversiveness of other infants' cries to the acoustic properties of their own infants' cries. The third study will determine long-term individual differences stability of the structural properties of cries. In addition, developmental changes in the acoustic properties of hunger cries will be measured, along with the differentiation of cries in different social/motivational contexts. The fourth study will explore the relations among perceived aversiveness of an infant's cries, soothability of the infant, and perceptions of infant difficultness. The dual focus of these studies on the structural and functional aspects of infant cries will yield a fuller understanding of the cry's role in early parent-infant adaptation.